The Physiology Core is a central component of the YCCMD and critical to the success of the Center. The Core is directed by Dr. Thomas Carpenter, and is comprised of three subunits. The first of these, the Histology and Histomorphometry subunit prepares undecalcified tissue sections and performs specialized staining of bone and histomorphpmetric analyses. The second subunit, Biochemical Markers of Bone Turnover offers assays for osteocalcin, bone specific alkaline phosphatase, tartrate resistant acid phosphatase, serum, P1NP, and the C-telopeptide of type 1 collagen (CTX) as a bone resorption marker. The third subunit, Bone Densitometry and Imaging offers pQCT and, in collaboration with Dr. is currently establishing a micro-computed tomographic (uCT) facility featuring a recently acquired Scanco 35 uCT scanner. These subunits, functioning as separate but interrelated components, work synergistically to provide a comprehensive approach to analyzing a wide range of animal models. The Physiology Core has been a focal point of entry for new and junior investigators in the field, and has greatly enhanced the productivity of Center members throughout the Medical School and in the larger University research community. Core utilization has included researchers from the Departments of Internal Medicine, Orthopaedics and Rehabilitation, Pediatrics, Surgery, Obstetrics and Gynecology, Genetics, Cell Biology, Immunobiology, Biology, Comparative Medicine, and Hematology. Our training efforts have had an even broader geographic reach. This overall structure has worked well and we will maintain the described organizational format for the next funding cycle. With increased demands for services and the invariable increase in operating expenses, we have had to meet certain fiscal challenges. Our cost recovery program has allowed us to operate with a balanced budget for 9 years. Moreover, with efficient management we have maintained a sufficiently modest fee structure as to limit rate increases, thereby minimizing the impact on junior and first time investigators.